Syndiotactic 1,2-polybutadiene fibers can be utilized as a tread base rubber in tires in order to improve their heat build-up and wear characteristics. However, in order for the syndiotactic 1,2-polybutadiene to provide the desired combination of properties, it is essential for it to be in fibrous form. For example, U.S. Pat. No. 4,274,462 discloses pneumatic tires having improved resistance against heat build-up which employ syndiotactic 1,2-polybutadiene fibers in their tread base rubber.
Various techniques for synthesizing syndiotactic 1,2-polybutadiene in organic solvents and water are known in the art. For example, U.S. Pat. No. 3,901,868 reveals a process for producing a polymer consisting essentially of syndiotactic 1,2-polybutadiene by the successive steps of:
(a) preparing a catalyst component solution by dissolving, in an inert organic solvent containing 1,3-butadiene, a cobalt compound, soluble in the organic solvent, such as (i) cobalt-.beta.-diketone complex, (ii) cobalt-.beta.-keto acid ester complex, (iii) cobalt salt of organic carboxylic acid, and (iv) halogenated cobalt-ligand compound complex, and an organoaluminum compound,
(b) preparing a catalyst composition by mixing the catalyst component solution with an alcohol, ketone or aldehyde compound and carbon disulfide,
(c) providing a polymerization mixture containing desired amounts of 1,3-butadiene, the catalyst composition and an inert organic solvent, and
(d) polymerizing 1,3-butadiene at a temperature of -20.degree. C. to 90.degree. C.
U.S. Pat. No. 4,429,085 reveals a process for producing polybutadiene composed essentially of syndiotactic 1,2-polybutadiene in an aqueous medium comprising polymerizing 1,3-butadiene in said aqueous medium in the presence of (1) a catalyst composition microencapsulated in a polyene product which contains (a) at least one cobalt compound selected from the group consisting of (i) .beta.-diketone complexes of cobalt, (ii) .beta.-keto acid ester complexes of cobalt, (iii) cobalt salts of organic carboxylic acids having 6 to 15 carbon atoms, and (iv) complexes of halogenated cobalt compounds of the formula CoX.sub.n, wherein X represents a halogen atom and n represents 2 or 3, with an organic compound selected from the group consisting of tertiary amine alcohols, tertiary phosphines, ketones and N,N-dialkylamides, and (b) at least one organoaluminum compound of the formula AlR.sub.3, wherein R represents a hydrocarbon radical of 1 to 6 carbon atoms; and (2) carbon disulfide.
After the syndiotactic 1,2-polybutadiene is synthesized utilizing a conventional technique, it is necessary to convert it to fibrous form. This is generally done utilizing hot mill flexing and/or extrusion techniques.